The following links provide information and technical guidance for Software Developers and Transmitters who are interested in developing software for the Modernized e-File (MeF) Form 1041. You will find the XML Schemas, Business Rules, and other useful information separated by tax year. Production & Acceptance Testing System (ATS) - Current Valid Schemas Tax Year Form Type 2021 1041 2020 1041 2019 1041 Modernized e-File (MeF) Schemas and Business Rules